Defects in molded containers such as glass bottles and jars are often related to defects in the associated molds of origin. For this reason, it is desirable in an automated manufacturing operation having a plurality of molds to possess the ability of identifying a specific molded container with its mold of origin, and of associating container defects with mold of origin for repair or replacement purposes. In an automated plant for manufacturing glass bottles, for example, a machine termed an individual section or IS machine includes a multiplicity of mold cavities and automated apparatus for feeding glass gobs through successive molds to blow the containers. The blown containers are then fed by suitable conveying apparatus to a lehr where annealing takes place, and then to a so-called cold end where inspection and sorting are performed prior to packaging of the containers for shipment. In view of the processing delay between the molding and inspection operations, it is desirable to identify potentially defective mold cavities at an early time in order to reduce scrap. In the same way, it is desirable after a mold cavity has been replaced or repaired to closely inspect containers from that cavity in order to certify proper operation.
U.S. Pat. No. 4,413,738 assigned to the assignee hereof discloses a system for one hundred percent inspection of molded containers for sidewall and finish defects, and for automatically sorting containers from mold cavities which are idenfied as defective. Each container is routed through one of a plurality of multistation inspection devices for automated optical inspection of container sidewall and finish. A primary one of the inspection devices includes or has associated therewith an automated cavity inspection device for reading a code molded into each container and thereby associating containers passing through that inspection device with molds of origin. A finished product computer correlates defects in bottles passing through the primary inspection device to defective molds. All containers are then routed through a second cavity identification device at which containers originating at the molds identified as defective by the finished product computer are sorted for rejection.
Although the inspection system disclosed in the referenced patent has enjoyed substantial commercial success and economic benefit in operation, further automation remains desirable. For example, there are container test which must be performed on a sampled basis, such as container volume, wall thickness and pressure tests, that are not incorporated in the disclosed system. Currently, it is necessary to manually sample containers in order to perform these tests, whereas it would be desirable to implement such tests on an automated-sample basis based upon mold cavity of container origin. A further desirable feature is to provide defective cavity information with clarity and rapidity in such a way that it may be readily employed at the hot end, either manually or in automated processes, for implementing replacement or repair of defective mold cavities. A general object of the present invention is to provide a system and method for inspection of molded containers which implement the aforementioned desirable improvements over the prior art of the referenced patent.
A more specific object of the invention is to provide a fully automated system and method for one hundred percent inspection of molded containers for sidewall and finish defects, and for automatic sampled inspection of containers for pressure retention, wall thickness, internal volume and the like on the basis of cavity of origin.
A further object of the invention is to provide a system and method of the described character which include facility for varying sampling rate for the sampled inspection tests as a function of cavity identification for enhanced tracking of suspect cavities and/or for rapid certification of new or repaired cavities.